It is well known in the tobacco art that the flavor and aroma of the smoke from the tobacco are very important considerations insofar as the ultimate consumer is concerned. There is extensive commitment by the manufacturers of smoking compositions to provide products that are acceptable to the consumer, particularly with respect to flavor and aroma characteristics. It has been the common practice in the tobacco industry to prepare blends of domestic and oriental tobaccos in order to provide smoking compositions which have a pleasing flavor and aroma during smoking. However, such blending is a costly practice and it is subject to the vagaries of tobacco filler supplies. In particular, burley tobacco is an advantageous component of smoking tobacco blends but it is of increasingly scarce supply and high cost.
As an alternative means of providing smoking compositions with desirable flavor characteristics, a variety of flavorants have been developed and proposed for incorporation into tobacco products. Illustrative of such tobacco flavorants are those described in U.S. Pat. Nos. 3,580,259; 3,625,224; 3,722,516; 3,722,516; 3,750,674; 3,879,425; 3,881,025; 3,884,247; 3,890,981; 3,903,900; 3,914,451; 3,915,175; 3,920,027; 3,924,644; 3,937,228; 3,943,943; 3,586,387; 4,379,754; and the like.
U.S. Pat. No. 4,036,237 describes smoking compositions which contain an aromatic beta-hydroxy ester flavorant such as ethyl 2,2-dimethyl-3-hydroxy-3-phenylpropionate, which volatilizes under smoking conditions.
U.S. Pat. No. 4,312,368 describes smoking compositions which contain a heterocyclic-hydroxy-substituted carboxylate flavorant-release additive such as ethyl 2-(2-butyl-3-hydroxy-3-methyl-3-(3-pyridyl)propionate. Under smoking conditions this additive pyrolyzes into 3-acetylpyridine and ethyl .beta.-methylvalerate flavorants.
J. C. Leffingwell et al "Tobacco Flavoring For Smoking Products" (R. J. Reynolds publication, 1972) includes a listing of desirable flavorants for smoking compositions.
Of more specific interest with respect to the present invention subject matter is the proposed utilization of substantially non-volatile reaction products of sugars with aminoacids as tobacco flavorants.
U.S. Pat. No. 3,478,015 describes "browning reactions" in which an amino acid and a sugar having an active carbonyl are reacted in a lower alkyl polyhydric alcohol solvent in the absence of water at a temperature less than 90.degree. C. for about 5-15 hours. The resultant reaction mixture is applied in an amount of about one percent by weight to tobacco as a flavorant additive.
U.S. Pat. No. 3,920,026 describes tobacco flavorants prepared by reacting valine with a carbonyl compound selected from sugars, dihydroxyacetone, or pyruvaldehyde. The reaction is conducted in a solvent such as glycerol or propylene glycol at a temperature between about 120.degree.-200.degree. C. for a period of 0.5-5 hours. The reaction mixture is applied directly onto tobacco, or it is separated into volatile and nonvolatile fractions which respectively are useful as tobacco flavorants.
U.S. Pat. No. 3,722,516 describes the addition of dihydroxyacetone alone or in combination with aminoacids to enhance the natural flavor characteristics of tobacco filler, such as the caramel-like or burned sugar-like flavor and aroma of the tobacco under smoking conditions.
Japanese Pat. No. 9239/71 discloses the use of sugar-aminoacid condensation products as tobacco "perfumes". The condensation product is produced by reacting an aminoacid with a sugar in an aqueous or alcohol solvent, and usually in the presence of an acid catalyst such as malonic acid. The desired compounds can be separated and purified by use of ion-exchange resins and thereafter applied to tobacco filler.
Japanese Pat. No. 3398/73 discloses certain other specific aminoacid-sugars that are synthesized from their respective components by the Amadori rearrangement, by heating at 130.degree. C. for fifteen minutes in the presence of a malic acid catalyst. The specific compounds are isolated, and can be combined with other ingredients such as cocoa to produce tobacco flavorants.
U.S. Pat. No. 4,306,577 describes the preparation of tobacco flavorant compositions by the reaction of a reducing sugar with an aminoacid in the presence of ammonium hydroxide. The reaction product is applied to tobacco filler in an amount between about 0.001-3.0% by weight of the filler blend. The primary effect of the addition of the reaction product to the tobacco is to overcome or alter the "stemmy" taste frequently associated with reconstituted tobacco products.
There is continuing research effort to develop improved smoking compositions which generate mainstream smoke with flavorant-enhanced taste and character under smoking conditions.
Accordingly, it is an object of this invention to provide smoking compositions having incorporated therein a flavorant component which is characterized by lack of mobility and/or volatility at ambient temperature.
It is another object of this invention to provide smoking tobacco compositions having incorporated therein a flavorant-release additive which under normal smoking conditions imparts improved flavor to mainstream smoke and improved aroma to sidestream smoke.
It is a further object of this invention to provide sugar derivatives which are adapted to be incorporated into cigarette fillers, and which under normal smoking conditions release volatile flavorant constituents into cigarette smoke.
Other objects and advantages of the present invention shall become apparent from the following description and examples.